<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>bootstrap</title>
    <link rel="stylesheet" href="css/bootstrap.min.css">
    <style>
    .main{
        width: 100%;
        background: #ccc;
        padding: 100px 0px;
    }
    </style>
</head>
<body>
<div class="container" style="background:red ;">占用百分之80左右</div>
<div class="container-fluid" style="background:blue ;">占用百分之100左右</div>
<div class="main" >
    <div class="container"> 这是一个100%</div>
</div>
</body>
</html>